How to Replace the CMOS Battery on Dell Optiplex

Overview

If your Dell Optiplex (or any PC) keeps forgetting BIOS settings or shows “system battery voltage is low” messages, the CMOS battery needs replacing. In this beginner-friendly tech tip, I show you how to quickly replace the CR2032 CMOS battery on a Dell Optiplex 745. The process is simple: power off, unplug, open the case using Dell’s tool-less design, access the motherboard, remove the old battery, insert the new one, and reconfigure BIOS settings. This applies to Optiplex 380, 745, 755, and most other desktop PCs.

Key Moments

• Recognizing low CMOS battery symptoms: voltage warnings and lost BIOS settings
• Opening Dell’s tool-less case design with latch mechanism
• Locating the CR2032 battery on the motherboard
• Removing hard drive cage for easier access
• Using pliers or screwdriver to release battery clip
• Installing fresh CR2032 battery from Amazon bulk pack
• Reconfiguring BIOS settings after battery replacement

Full Transcript (Edited)

Hi there YouTube, today I’m going to show you another tech tip for beginners. If you ever power up one of these Dell machines, or any other machine, that says “system battery voltage is low,” or if every single time that you power off and disconnect the power on your computer and you have to go through setup to configure all your drives again, it may be that the system battery is low.

Now in this Dell desktop, the actual motherboard detects that the battery is low. And if I were to reset my settings right now and reboot, it’ll keep on saying “system battery is low, system battery is low.” So I’m gonna quickly show you right now how to go ahead and replace the CMOS battery on these things. It’s very simple. It’s something that every beginner in computer repair should know.

So let me show you. First thing is I’m going to turn off… this is, by the way, a Dell Optiplex 745. First thing I’m going to do is I’m going to power it off, unplug the power. And this computer is opened by a latch mechanism, so I’m going to go ahead and pull this latch and the side cover comes off.

As you can see here, this is a very modular computer. Most of these Dells are, and everything comes off using clips, with the exception of some other plastics that require some screws. But to get to the CMOS battery, if you can see down here, that’s the battery that we need to replace right there.

I’ve already gone ahead and purchased a set of batteries from Amazon. As you can see, I’ve already done several of these other systems that I have. Every single one has had a bad battery in it. So these are CR2032.

What I’m gonna do here is I’m gonna take this hard drive out of the way so that we can easily access that. So in this computer, just press this to lift it up and we can move it out of the way.

The way that this computer’s cooling system is set up is kind of cool too. So this is like a solid heatsink and then this is the fan that kind of cools the hard drive and the CPU by blowing air that way.

What I’m going to do is I’m going to use a pair of pliers that I had that I use for this. You can also use a screwdriver, but if you see the battery, there’s this little clip here. Sorry, I’m doing this without looking, but if I squeeze, that battery comes off. So I can just lift it out and put it in my recycle pile.

And I get a brand new one from my pile and I insert it by putting it underneath this lip here and then I just push down. That’s it!

Now I reverse the process of putting the hard drive back in and I power up the computer. First thing, supply electricity and press the power button. And now it’s gonna complain again that the battery is low one more time.

But in this case I go to the BIOS. I press F2. This computer, I don’t have a floppy drive, so I’m going to disable the floppy drive. And that’s it. I mean, you can go ahead and set the date and time, but what I do is I usually do that in Windows. But you should do that here if you’re installing the operating system from scratch.

And yeah, all you’re going to do is set the settings that you need in the BIOS and save and exit. And the next time that this powers up, you will not get a low battery message.

That’s it! Now it’s starting Windows and I really hope you find this useful. Let me know in the comments what you think. Until next time!